已知xy=9,x-y=-3,求a^2+3xy+y^2的值

问题描述:

已知xy=9,x-y=-3,求a^2+3xy+y^2的值

x²+3xy+y²
=(x²-2xy+y²)+5xy
=(x-y)²+5xy
=(-3)²+5×9
=9+45
=54